SPOKANE, Wash. — Conservation groups say they plan to sue the state of Washington for allowing suction dredge mining in rivers and streams that are home to endangered salmon and steelhead.

The state Department of Wildlife grants permission for the gold-mining technique in rivers throughout the state.

Conservation and fisheries groups have also introduced bills in the state Legislature to better regulate the practice.

Suction dredge mining uses large, gas-powered vacuums to suck up gravel on the bottom of rivers and streams in search of gold flakes. The gravel beds are critical to salmon spawning.

The Center for Biological Diversity and the group Cascadia Wildlands have filed a 60-notice of intent to sue the state in federal court.